Index: releng/11.4/stand/common/interp.c
===================================================================
--- releng/11.4/stand/common/interp.c	(revision 361553)
+++ releng/11.4/stand/common/interp.c	(revision 361554)
@@ -1,173 +1,182 @@
 /*-
  * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 /*
  * Simple commandline interpreter, toplevel and misc.
  *
  * XXX may be obsoleted by BootFORTH or some other, better, interpreter.
  */
 
 #include <stand.h>
 #include <string.h>
 #include "bootstrap.h"
 
 #define	MAXARGS	20			/* maximum number of arguments allowed */
 
 /*
  * Interactive mode
  */
 void
 interact(void)
 {
-	static char	input[256];			/* big enough? */
+	static char		input[256];		/* big enough? */
+	const char * volatile	interp_identifier;
 
+	/*
+	 * Because interp_identifier is volatile, it cannot be optimized out by
+	 * the compiler as it's considered an externally observable event.  This
+	 * prevents the compiler from optimizing out our carefully placed
+	 * $Interpreter:4th string that userboot may use to determine that
+	 * we need to switch interpreters.
+	 */
+	interp_identifier = bootprog_interp;
 	interp_init();
 
 	printf("\n");
 
 	/*
 	 * Before interacting, we might want to autoboot.
 	 */
 	autoboot_maybe();
 
 	/*
 	 * Not autobooting, go manual
 	 */
 	printf("\nType '?' for a list of commands, 'help' for more detailed help.\n");
 	if (getenv("prompt") == NULL)
 		setenv("prompt", "${interpret}", 1);
 	if (getenv("interpret") == NULL)
 		setenv("interpret", "OK", 1);
 
 	for (;;) {
 		input[0] = '\0';
 		interp_emit_prompt();
 		ngets(input, sizeof(input));
 		interp_run(input);
 	}
 }
 
 /*
  * Read commands from a file, then execute them.
  *
  * We store the commands in memory and close the source file so that the media
  * holding it can safely go away while we are executing.
  *
  * Commands may be prefixed with '@' (so they aren't displayed) or '-' (so
  * that the script won't stop if they fail).
  */
 COMMAND_SET(include, "include", "read commands from a file", command_include);
 
 static int
 command_include(int argc, char *argv[])
 {
 	int		i;
 	int		res;
 	char		**argvbuf;
 
 	/*
 	 * Since argv is static, we need to save it here.
 	 */
 	argvbuf = (char**) calloc((u_int)argc, sizeof(char*));
 	for (i = 0; i < argc; i++)
 		argvbuf[i] = strdup(argv[i]);
 
 	res=CMD_OK;
 	for (i = 1; (i < argc) && (res == CMD_OK); i++)
 		res = interp_include(argvbuf[i]);
 
 	for (i = 0; i < argc; i++)
 		free(argvbuf[i]);
 	free(argvbuf);
 
 	return(res);
 }
 
 /*
  * Emit the current prompt; use the same syntax as the parser
  * for embedding environment variables. Does not accept input.
  */
 void
 interp_emit_prompt(void)
 {
 	char		*pr, *p, *cp, *ev;
 
 	if ((cp = getenv("prompt")) == NULL)
 		cp = ">";
 	pr = p = strdup(cp);
 
 	while (*p != 0) {
 		if ((*p == '$') && (*(p+1) == '{')) {
 			for (cp = p + 2; (*cp != 0) && (*cp != '}'); cp++)
 				;
 			*cp = 0;
 			ev = getenv(p + 2);
 
 			if (ev != NULL)
 				printf("%s", ev);
 			p = cp + 1;
 			continue;
 		}
 		putchar(*p++);
 	}
 	putchar(' ');
 	free(pr);
 }
 
 /*
  * Perform a builtin command
  */
 int
 interp_builtin_cmd(int argc, char *argv[])
 {
 	int			result;
 	struct bootblk_command	**cmdp;
 	bootblk_cmd_t		*cmd;
 
 	if (argc < 1)
 		return(CMD_OK);
 
 	/* set return defaults; a successful command will override these */
 	command_errmsg = command_errbuf;
 	strcpy(command_errbuf, "no error message");
 	cmd = NULL;
 	result = CMD_ERROR;
 
 	/* search the command set for the command */
 	SET_FOREACH(cmdp, Xcommand_set) {
 		if (((*cmdp)->c_name != NULL) && !strcmp(argv[0], (*cmdp)->c_name))
 			cmd = (*cmdp)->c_fn;
 	}
 	if (cmd != NULL) {
 		result = (cmd)(argc, argv);
 	} else {
 		command_errmsg = "unknown command";
 	}
 	return(result);
 }
Index: releng/11.4
===================================================================
--- releng/11.4	(revision 361553)
+++ releng/11.4	(revision 361554)

Property changes on: releng/11.4
___________________________________________________________________
Modified: svn:mergeinfo
## -0,0 +0,2 ##
   Merged /head:r361295
   Merged /stable/11:r361538